title: Corticospinal tract asymmetry and handedness in right- and left-handers by diffusion tensor tractography.
abstract: OBJECTIVE
  Cerebral hemispheres represent both structural and functional asymmetry, which differs among right- and left-handers. The left hemisphere is specialised for language and task execution of the right hand in right-handers. We studied the corticospinal tract in right- and left-handers by diffusion tensor imaging and tractography. The present study aimed at revealing a morphological difference resulting from a region of interest (ROI) obtained by functional MRI (fMRI).
  
  
  METHODS
  Twenty-five healthy participants (right-handed: 15, left-handed: 10) were enrolled in our assessment of morphological, functional and diffusion tensor MRI. Assessment of brain fibre reconstruction (tractography) was done using a deterministic algorithm. Fractional anisotropy (FA) and mean diffusivity (MD) were studied on the tractography traces of the reference slices.
  
  
  RESULTS
  We observed a significant difference in number of leftward fibres based on laterality. The significant difference in regard to FA and MD was based on the slices obtained at different levels and the laterality index. We found left-hand asymmetry and right-hand asymmetry, respectively, for the MD and FA.
  
  
  CONCLUSIONS
  Our study showed the presence of hemispheric asymmetry based on laterality index in right- and left-handers. These results are inconsistent with some studies and consistent with others. The reported difference in hemispheric asymmetry could be related to dexterity (manual skill).
authors.affiliation: INSERM UMR 1101, LaTIM, Université de Brest, Brest, 29200, France, romuald.seizeur@chu-brest.fr.
authors.forename: Romuald
authors.initials: R
authors.lastname: Seizeur
authors.forename: Elsa
authors.initials: E
authors.lastname: Magro
authors.forename: Sylvain
authors.initials: S
authors.lastname: Prima
authors.forename: Nicolas
authors.initials: N
authors.lastname: Wiest-Daesslé
authors.forename: Camille
authors.initials: C
authors.lastname: Maumet
authors.forename: Xavier
authors.initials: X
authors.lastname: Morandi
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011712:Pyramidal Tracts / Q000033:anatomy & histology*; D012016:Reference Values; D055815:Young Adult